Optical location systems

Abstract

An optical location system having a beam projection device (11, 51, 12, 13) to illuminate the field of view, and a detector array (29) to detect reflected light (21) from the field of view. The projected beam (13) is incrementably progressed across the field of view and for each increment the reflected points of light (61) detected by the detector (29) are recorded to build a map of the field of view, which is stored as a sparse array having as its first coordinate the angle of projection (A) of the illuminating beam (13) and as its second coordinate the azimuth angle (B) of the reflected ray detected by the detector. The value stored in each element of the array is the angle of the incidence (C) of the horizontal component of the detected ray with the detector.

I claim: 
     
       1. An optical imaging and location system comprising: projection means situated at a first known location and arranged to project a beam of radiation into a field of view in a direction subtending a variable angle with a reference base line;   detection means spaced a predetermined distance from said projection means along said base line and including a lens and a detector array arranged so that a reflected ray of radiation from an object in said field of view is directed by said lens substantially onto one element of said detector array, said detector array having a first dimension the co-ordinate of which represents a value of an angle of incidence between said reflected ray in a horizontal reference plane and said base line, the value of said angle of incidence being determined by detecting the respective element in said first dimension of said detector array onto which a peak intensity point of said reflected ray is directed by said lens; and   storage means for storing a spatial map of said field of view comprising a sparse array having one fewer dimension than said field of view, one dimension being addressed by a value representing said variable angle and, a plurality of cells, one of said cells being arranged to store the value of said angle of incidence.   
     
     
       2. The optical imaging and location system as claimed in claim 1, wherein said field of view is a three dimensional space and said sparse array is a two dimensional array one dimension of which is addressed by a value representing said variable angle and the other dimension of which is addressed by a line number corresponding to a line of elements in said first dimension of said detector array, said line number being representative of an elevation angle of said reflected ray subtended with said horizontal reference plane. 
     
     
       3. An optical imaging and location system comprising: projection means situated at a first known location and arranged to project a beam of radiation into a field of view comprising a three dimensional space in a direction subtending a variable angle with a reference base line;   detection means spaced a predetermined distance from said projection means along said base line and including a lens and a detector array arranged so that a reflected ray of radiation from an object in said field of view is directed by said lens substantially onto one element of said detector array, said detector array having a first dimension the co-ordinate of which represents a value of an angle of incidence between said reflected ray in a horizontal reference plane and said base line, the value of said angle of incidence being determined by detecting the respective element in said first dimension of said detector array onto which a peak intensity point of said reflected ray is directed by said lens; and   storage means for storing a spatial map of said field of view comprising a sparse array having one fewer dimension than said field of view, one dimension being addressed by a value representing said variable angle, and a plurality of cells, one of said cells being arranged to store the value of said angle of incidence;   said sparse array being a two dimensional array one dimension of which is addressed by a value representing said variable angle and the other dimension of which is addressed by a line number corresponding to a line of elements in said first dimension of said detector array, said line number being representative of an elevation angle of said reflected ray subtended with said horizontal reference plane;   said one cell of said sparse array storing a value representative of said angle of incidence corresponding to the position along said line of elements determined by locating the element onto which the peak intensity point of said reflected ray is directed by said lens in the plane defined by said line of elements and an intensity value of the reflected ray for which the angle of incidence is recorded.